Interception trainer



Jan. 18, 1949. c. J. CRANE ETAL INTERCEPTION TRAINER '7 Sheets-Sheet 1Filed Feb. 26, 1940 /vo/vq A. 87-007- Ir N ' v 4&- RA EYJ Jan. 18, 1949.c. J. CRANE ETAL INTERCEPTION TRAINER '7 Shets-Sheet 3 Filed Feb. 26,1940 GEORGE 14/7 04 LO/VAA/ CARL 714/ 704. 4.5

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INTERCEPTION TRAINER Filed Feb, 26,';94o 7 Sheets-Sheet 4 Jan. 18, 1949.c. J. CRANE EIAL INTERCEPTION TRAINER Filed Feb. 26, 1940 7 Sheets-Sheet5 /N V15 N 7'01? 5 C424 J. CRH/VE GEORGE 11/704 4on4 0,424 W/7(/LL&EEr/Mo/vo A. 670a r -x 1949- c. J. CRANE ETAL INTERCEPTIQN TRAINER 7Sheets-Sheet 6 Filed Feb. 26,. 1940 Patented Jan. 18, 1949 INTERCEPTIONTRAINER Carl J. Crane and George V. Holloman, Dayton, Carl W. Muller,Osborn, and Raymond K. Stout,

Dayton, Ohio Application February 26, 1940, Serial No. 320,880

(Granted under the act of March 3, 1833, as amended April 30, 1928; 3'700. G. 757) 6 Claims.

The invention described herein may be manufactured and used by or forthe Government for governmental purposes, without the payment to us ofany royalty thereon.

This invention relates in general to improvements in auxiliary apparatusused in combination with aviation ground trainers and more particularlyrelates to a novel arrangement of transparent recorder table surfaces,one of which sur faces supports a simulated air borne or sea bornetarget propelled at a constant speed and having a controlled directionand another of which surfaces supports a course indicator, or recorder,controlled by the aviation ground trainer, whereby simultaneousobservation of the relative position of the recorder and the targetpermits the solution of interception problems;

At the present time instruction in complicated aviation flight problemsis given on aviation ground trainers, such as the well-known Linktrainer, with a consequent reduction in actual flying time necessary tocomplete the course of instruction. The structure and operation ofsuchtrainers is disclosed in United States Patents Nos. 1,825,462 and2,099,857, granted to Edwin A. Link, Jr.

It is customary in the operation of aviation ground trainers to use inconjunction therewith, a course indicator, or recorder, which comprisesa frame supported by a plurality of rollers, each of the rollers beingrotatable about a vertical axis to cause a change in direction ofrotation of the rollers. The rollers are mounted on vertical shafts,which are interconnected by gearing to a selsyn receiver mounted on therecorder frame. The selsyn receiver is electrically connected to aselsyn transmitter, driven by the trainer as it rotates about a verticalaxis, so that the recorder rollers are always rotated through the sameangle as the trainer and the heading of the recorder thus corresponds atany instant with the heading of the trainer. At least two of thesupporting rollers of the recorder are driven by small electric motorsgenerally of the synchronous type, so that the speed of the recorderover the map table represents to a definite scale the simulated velocityin flight of the trainer. The speed of the recorder, or course indicatoris kept constant, but

may be adjusted to any desired value by changing the speed of thegenerator supplying current to the propulsion motors on the recorder.

Course recorders such as above described generally employ one of thesupporting rollers as a marker wheel, which when inked by a felt pad,

traces the course of the recorder on the record 2 map, though theposition of the marker wheel even when not inked serves as a courseindicator.

For a more complete description of course recorders suitable for usewith aviation ground trainers, preference may be had to United StatesPatent No. 1,293,747, to Hannibal C. Ford and to United States PatentNo. 2,179,663, granted to Edwin A. Link, J1.

In a course of instruction on the ground trainer, it is desirable to beable to solve interception problems, for example to simulate flightintercepting another aeroplane, or water borne target, knowing thecourse and speed of the target under either simulated fair Weatherconditions, or under simulated bad weather conditions, necessitatingsimulating instrument flight either in Whole or in part. A. means torender such instruction possible is provided by the invention, in whicha record map table is provided with a plurality of record surfacesarranged in a rack in the form of shelves and preferably made of atransparent material such as glass, or one of the well-known transparentplastic materials. The target to be intercepted is placed one of thesurfaces, which has suitable course indicia marked thereon and thetarget is set into motion with a velocity and under a controlled headingin accordance with the desire of the instructor and the trainer courserecorder is placed in operation under the directional control of thetrainer and at a velocity proportional to the simulated air velocity ofthe trainer and starting at a definite point and with a known. heading.The instructor then informs the student of the course and simulatedvelocity of the target, who then must solve the vector problem tointercept the target at the proper point. The movement of the courserecorder relative to the target is at all times visible to theinstructor and the record trace upon the record surfaces leaves apicture of the completeness of the problems solution. 1- simulatedtrainer flight may be wholly on instru ments, or may simu ate fairweather flight, the student observing the position of the courserecorder relative to the target alter simulating flight for a timesufficient to bring the target into view, if the same were in actualflight, so that the resulting solution of the problem becomes apparent.

Since it is essential to take into account the effect of simulateddrift, on either the air borne or water borne targets and also theeffect of winds on the trainer, the invention provides a means forcorrectly simulating such eifects by means of a device permitting therecorder and targets to be displaced in a direction and at a velocityproportional to the effect of a simulated air current on the trainer orair borne target and to the effect of water currents on the water bornetarget.

Analogous to the solution of interceptionproblems is the simulation ofcontrol of trafiic of a plurality of aircraft operating at differentaltitudes approaching the same destination and required to proceed to alanding in accordance with their order of arrival and their respectivealtitudes. Such trafiic control problems may be readily solved with thetrainer record table used according to the invention, by providing aseparate record surface in the form of a shelf for each trainer to beoperated and the instructor can then watch the respective recorders andgive to each student the proper informationas to the conduct of hisrespective simulated flight, in the same manner that a traffic controldirector at a large airport conducts the safe landing of a number or"aircraft arriving at close intervals of time. It merely requires thesupplying of'the proper maps and charts in order to convert from onetype of problem to another.

It is an object of this invention to'provide apparatus for aviationground training in which a multiple surface record table serves as asupport for one or more simulated air borne or water borne targets, eachhaving a controlled velocity and direction on one of said surfaces andone or more course indicators, or recorders, each directionallycontrolled by a respective ground trainer and operating at a velocityproportional to the simulated flight velocity of the trainer, wherebyflight interception problems may be simulated.

A further object of the invention is the provision of a novel trainertable assembly comprising a plurality of superimposed spaced transparentsurfaces, each surface having position indicia thereon, whereby theinstantaneous relative position of a ground trainer .courseindicator anda simulated air borne or a water borne target may be observed.

Another object of the invention is the .provision of a means to cause amovement of a course indicator for an aviation ground trainer relativeto its record surface, in a manner to simulate the eiTect of a windacting on said trainer, while in simulated aircraft flight.

A further object of theinvention is the provision of a means foraffecting the movement of a recorder, simulating in velocity anddirection, the movement of an air borne or'water borne craft in a mannerequivalent to the effect on said craft of an external force such as windor water currents respectively.

A further object of the invention is the provision of a novel trainertable assembly permitting simultaneous operation of a plurality ofaviation ground trainer recorders thereon, whereby simultaneoussimulated flights of a plurality of aviation ground trainers may bedirected'by an instructor.

Other objects of the invention will appear by reference to thespecification and the appended drawings forming a part thereof and inwhich:

Fig. 1 illustrates a trainer record table having superimposed recordsurfaces, one of which surfaces cooperates with a simulated air or waterborne target and another of said surfaces cooperates with a courserecorder controlled'by 'an aviation ground trainer;

Fig. 2 illustrates anenlargedview of a, simulated water borne target, asemployed in the invention;

Fig. 3 illustrates an enlarged view of the device illustrated in Fig. 2,showing the driving mechanism;

Fig. 4 is a vertical cross sectional view .of Fig. 3;

Fig. 5 illustrates a simulated water borne target similar to the deviceof Figs. 2, 3 and 4 modified for use with distant speed and directioncontrols;

Fig. 6 is a vertical-cross sectional view of Fig. 5;

:Fig. '7 illustrates the means employed fordistantlyscontrolling thespeed and direction of the targets illustrated in Figs. 5 and 6;

Fig. 8 illustrates an enlarged view of a simulated air borne targetemployed in the invention;

Fig. .9 illustrates a vertical section of a modified trainer recordtable assembly permitting wind or water current drift efiects to besimulated;

Fig. 10 is a top' plan view of the-deviceofFig. 9;

Figure 11 is an illustration oftwo ofthe trainer record table devices ofFigures 9'an'd lo-superimposed and used to replace the tables of thedevice of Figure 1.

Fig. 12 .is a top plan View illustrating an aviation ground trainerand'table array permitting traffic control problems to be solved; and

Fig. 13 is a frontelevation showing the ar rangement illustratedinF-ig.'12.

Referring to Fig. 1, the reference .numeral I generally indicates arecord map table having thereon an .upper supporting surface 2 andspaced therefrom and parallel therewith, a lower supporting surface 3arranged in theform of a shelf. The upperand lower surfaces are.preferably made of a transparentmaterial .such as glass or any ofthetransparent syntheticresinous materials where it is desired to usethe table for the solution of course interception problems.

The .upper and lower surfaces .2 andliare each ruled with suitableindicia i,,such aslines indicating latitude andllongitude, representingapart of the surface of .thetearth, either landior water and the indiciaare ruled so as-toibeiidentical when superimposed.

An aviation ground trainerfi is placed adjacent the trainer. record.table i .and .iselectrically. conthe surface 3.

.nected through the-electric selsyn-.transmission conductorsfi to acourse recorder 7,. movable over one of the record surfaces and shown,as being The recorder l is supportediby a plurality of rollers 8, one ofwhich-serves as a marker wheel to leave an inked-trace'ofthe recorderpath on the'recordsurface 53. Generally the recordersiare providedwith'three rollers,"two .of whichxare drivenby small electric motors(not shown) supplied with currentvby the conductors :9. The motors drivetherecorderl over the surface 3 at a'constant speed, representingtoa-predetermined-scale, the simulated velocity of flight of the trainer5. "i'he rollers '8 are mounte'd'on vertical shafts, which areinterconnected by gearing with a selsyn receiver (not showmgwhich inturn is connected by'the conductors 6'to a selsyntransmitten rotated bythe trainer 5 as it changes 'its heading. The directionalheading of therecorder rollers 8 are thussimultaneously rotated in step with therotation of .the trainer and the course taken by the recorder in itsmovement relative to'the surface'3, is thus controlled by the heading ofthe trainer. '.The .construction of the recorder and its control lby thetrainer,

asbefore noted, is we'll known inthe art and the shown) detailconstruction of the recorder and its control, therefore, has not beenillustrated in the drawings.

As seen in Fig. 1, a simulated water borne target I0, is adapted to bepropelled over the record surface 2 at a velocity proportional to thesimulated velocity of a target vessel on the ocean and is adapted to bedirectionally controlled at the will of the instructor. One form of thesimulated water borne target If) is illustrated in Figs. 2, 3 and 4 inwhich the target comprises a hull shaped casing i I, supported formovement over a record surface by two pairs of rollers l2 and I2respectively. As seen in Fig. 2, the casing H has two manuallycontrolled knobs thereon, the knob 33, controlling the plane of rotationof the rollers l2 and I2 and the knob 39, controlling the speed settingof a rheostat governing the speed of the driving motors. A suitablescale reading indegrees of rotation and simulated speed in knots isplaced adjacent the respective knobs 33 and 39, so that their respectivesettings may be observed.

As seen in Figs. 3 and 4, the propelling mechanism comprises a frame [4,secured to the casing II as by bolts, the frame having enlarged bossesl5 and I5, which serve as bearings for the vertical shafts l3 and iii.The shafts l3 serve as supports for the rollers l2, which are rotatablymounted on the lower ends of the shafts. Small electric motors I6 aremounted on the shafts l3 and are rotatable therewith. The motors It maybe of the well-known universal type, which can be energized from anysuitable low voltage alternating or direct current source. The shaftsI6, of the motors [5, pass through suitable journal openings transverseto the axis of shafts l3 and have pinion gears I! mounted on the endportions of the shafts. The pinion gears l'l mesh with idler gears l8rotatably mounted on pivots carried. by the shafts The idler gears l8each mesh with a driving gear l9 secured to each of the rollers 12 androtatable therewith. The motors I6 each have secured thereto a pair ofbrushes and 22, which contact the respective slip rings 2| and 23mounted on the bosses 15. The slip rings are connected'in parallelby apair of conductors 31 to a'powe'r source (not Each motor [6, whenenergized from the power source, will drive a respective roller l2through the medium of pinion gear IT, idler 7 gear 18 and driving gear19, at a speed proportional to the motor speed. The motor speed isadjusted to give a desired speed of translation to the target If bymeans of a variable resistance 34, inserted in series with one of theconductors 31. The resistance 34 may be varied by rotation of the arm 35by the shaft 35. The shaft 36 carries the manual adjustment knob 39, asseen in Fig. 2, so that the speed of the driving motors [6 may be set atany desired value by rotation of the knob 39. The motors l6 preferablyare provided with built in reduction gearing, so that the normal speedof the shafts IE will be a desired small number of revolutions perminute.

Upon their upper ends, the shafts l3, each carry a gear 24, which meshwith a gear 25, rotatably -mounted on the upper end of the shaft 21,rotatably mounted in frame M. The vertical shafts l3 are rotatablymounted in the bosses I5 and the rollers l2 are rotatablymounted onpivots carried by the lower ends of the shafts I3. At their upper ends,the shafts l3 are each provided with a gear 26, meshing with the gear25.

' The shaft 21 carries a bevel gear 28 adjacent its conductors 31.

6. lower end and the gear 28 meshes with a bevel gear 3!, mounted on theinner end of the shaft 32. The shaft 32 is suitably supported by theframe [4 and at its outer end carries the knob 33. Rotation of the knob33 causes rotation of gears 3i and 23, shaft 2'1, gear and gears 24 and26. Rotation of gears 24 and 26, causes the plane of rotation of rollersI2 and I2 to be rotated in equal angular increments. The knob 33 thusserves as a means to alter the heading of the target III at the will ofthe instructor.

A vertical shaft 29 is secured to the lower end of the shaft 2'! and iscoaxial therewith. The shaft 29 terminates in a fork in which the markerroller is rotatably mounted. The roller, when inked by an ink saturatedfelt, will trace the recorder path on a record sheet and is rotatable inunison with the rollers 12 and I2 by the knob 33.

The target [0 is placed in operation by the instructor by aligning thetarget roller planes with a line on the table surface 2 and thenrotating the knob 33 until the desired heading is obtained. The knob 39is set to operate the motors H5 at the desired speed to give a velocityof translation having a definite ratio to the simulated velocity of awater borne craft and the motors are then energized by connecting theconductors 37 to the power source through a suitable switch (not shown).

Figs. 5, 6 and 7 illustrate a modified form of driving and controlmechanism for the target [0, illustrated in Fig. 2, and similar partsare given the same reference numerals as in Figs. 2, 3 and 4. Theconstruction, as seen in Figs. 5 and 6, differs from the drivingmechanism illustrated in Figs. 3 and 4, in that the electric motors [6are replaced by synchronous motors is which are adapted to run at aspeed determined by the frequency of the alternating current supply forthe motors, but the driving mechanism to the rollers I2 otherwiseremains the same. The shaft 21 for the gear 25 is replaced by the rotorshaft 21' of a selsyn receiver 40, mounted on the recorder frame Id. Thegear 25 is thus rotated in unison with the rotor of the selsyn receiver40. The shaft 22 and marker roller 30 are mounted on the lower end ofthe shaft 21' of the selsyn receiver 40 in the same manner asillustrated in Figs. 3 and 4. The selsyn receiver is adapted to beconnected to a selsyn transmitter by means of the conductors 4| and themotors I are adapted to be connected to a controlled frequencyalternating current supply, by means of Rotation of the rotor of theselsyn receiver M3 thus controls the azimuth heading of the target ID inthe same manner as the manual control knob 33 and the speed of motorsI65, and hence the velocity of the target can be controlled by controlof the frequency of the alternating current supply for the motors.

The distant control mechanism for controlling the selsyn receiver andthe frequency of the alternating current supply for motors I65, isillustrated in Fig. '7, in which the reference numeral t2 indicates avariable speed electric motor supplied with direct current by conductors43 and controlled by a variable resistance 44, which may nple beconnected in series with the arma and field for a series wound motor, orconnected in the armature circuit of a shunt wound motor. The motor 42,is connected to drive a small alternator 45, which supplies current tothe conductors 3'1" at a frequency proportional to the speed of rotationof the motor instruments in bad weather.

regenerate instructor by adjustmentofthe rheostaltfld, which willcontrol the speed ofwmdtomfl and ':'the..fr e-- :quencysof thecurrent-generated: by.-the alternator 45, which in turn controls :theispeedcof .i th'emyn- The motors 4:155

.chronous driving motors x1165.

ma be purchased with 'sbuilt inzgear"reductions wsimil'artoithatabovedescribed with sreference to 1 the universal:motors-d5,xthus:permittingthe tareet-t be driven at a very slow speed.

' The selsyn-receiver lli: (Figure'fi) is connected by theleads H to a:selsyn transmitter 50,?the

trot-or .of which canbe revolvedwbyithesknob l,

:so that the directional-heading.oftthectarget- I0 may be controlled byrotating the knob 5|. The stator windings of the selsyn': receiver4lland .thefiselsyn transmitter "are supplied by a constant frequencysource of alternatingcurrentnot .trol knob 5i and-the rheostatM servetor-respec- *tlveiy maintain theiheading and :velocity: of the target asdesiredby: the instructor. Themotor 1 generator set and the -.selsyncontrolm-ay be placed in the cabinet indicated by the: referencecharacter la (Fig. .1) .placed adjacent --the instructors position, onthesideof the recordttable frame.

Fig. '8' iilustrates'the simulatedfair borne target which. may be? usedin interception problems ..inthe same-manner as the simulated sea bornefhe targeted has the outline. of an aeroplaneiand is supported onrollers MEI; :which target '1 d.

are :adapted to be driven and directionally 'controlled in the samemanner as above "described with reference to Figshzto 7.=inclusive. -Asmall .c red roller is .usedas-a marker-wheel similar in -Iunction tothe roller '38 of the device illustrated in Figs, .2-to -7, inclusive.Thmtargetfifi maybe manually controlled by .course: and (speed controlknChSQBand-ES, in the-.samemanner -as illustratedin Figs. l 34 and 4, orthe target may-be distantly controll d in theHma-nner'illustrated'inFigs. 5 to '7 .inclusive.

Aninterception problem .is solved .by .the in- -structor setting eitherone .or more ltargetssl-fl, or fill, into operationon .thesurface'2,..of .table I, .with a desired heading and with .a velocityproportional to the simulated .air velocity, or water velocity, or the.target craft .to be represented. Thetrainer' isthen placed inoperationWithlthe recorder l ,parallel .to the headingof. the wtrainer and thcourse .andsimulated yelocity v.ofthe target is giventothestudentaurally. Thecstudent must then solve a vector'problem tovobtain the.proper course .tosimulatawm .orderzto intercent the target or :60.The-instructor, beingl telephonic communication 'with the student, canat any time alter'the speedanddirection of the target and informing thestudent of the change, add additional elements to the problem. Thesimulated trainer flight maybe madeto representthe flying infairweather, or'flying by Where the table surfaces are made oftransparentmaterial, the indicia on the surfaces .2 and 3, permit theinstructor to watch'all phases in the solution of the problem and therecord traces left .onthe surfaces by the inked .markerwheels.,.serve..as a meansto visualize the solution ofthe problem andany errors therein caused by improper simulated "flight by the studentin'the trainer.

. 78 In .;;the :solution :of interception problems as sabove Edescribed,it-is important totbe -abl'e to introduce the efi'ect of simulatedWinds:acting -ron :bothathe trainer-end the isimulatednairuborne :targeto'r intheeaseof-the simulated iwatertborne target, the :eiiect .tofcurrents or other..-.factors acausingi-drift. i-Atmeans -.-to -simulate.such air or J Mater currenteeifects is illustrated in Figs. 9 and'-l0,- :ln which t-heinumeral. liltindicates. eachoffour lfi ftubularverticali-supports; each :provided with :zrollers i i, ,pivotaliy.mountedron the lower -.ends .thereof and. adaptedrto. beiinlroliingvcontact with ..1theesurfacccofva door. The rollers I'll .mayIbeeprovid'ed:withsuitablebrake devices (not shown) y 5 T1170 lretain thesupportsiin a fixed .,position .on the .floor. The supports ill! tareretained insspaced trelationsand' serve to supporti e. light. metaltrans- ;verse Tframe :generally "indicated .by the numeral 12.lThelira-me 12 comprises transverse side .rails :13. and TM spacecl by.the.zcentrally-idisposed cross- .tie T15 .and the .iplatamembers 7.6 andi 71, placed 'at-lthc.respective-endscof the frame. .Thesidrailsliitenninateat each end in spaced enlarged .bosses "1.8,, which.serve .as guides -in which the -yertical Ltuhular supports 7d -.areplaced. .The

loosses $1.18 are-.proiri'cledwith ciamping screwslli v so...that itheframe TZ may be a'djusted vertically ...on"thel-.supports 'fThe.crosstie" l5 isprovided with an-enlargedlbossiw -.whioh serves .as aguide land. clamping .means .for the vertical shaft 8! which-carriesai'ilange l821at1its outer end, to Jwhih is secured the'recor'd-table'83, which may .have a transparent. recordsurface such asabove described withrference'to suffaces'iZ and "-3 of the deviceofFigJl. .At one end .of theiframeil'2, .a roll s'haftit' lis rotatably(mounted transverse .to the "frame". axis, bybeai'ing'bosses"85, formedinlthe "frame membersillt'an'dll. The roll shaft 84 has a wormwheelllBii and a, pulleyitl mounted thereon, adjacent the frame member"'53. The worm wheel 86 is driven'by a worm "88 mounted insuitable'bearings carried by the plate'ilt. The .worrn'fit'is driven bya reversible adjustable speed electric 'motorila, alsomounted on"theiplate I6.

*A 'fiexible endless belt idfltpasses over'th'e pulley 81 foyer anadjustable"idler'pulley '9!', onto a ifpulley 9|, secured "to .a. secondroll shaft 92, mounted transversely to the frames "1 3 and "15,: inbea'ringi'besses 9'3. 'spooloi-"drumtt is secured "is secured tothe'shaft 92 Archer "97' is rotatably mountedon the frames "-TS'and14ttransversely thereof, adj a'centthe drum 95' andthe mounting made"adjustable longitudinally by 'means 'not "shown, "and a similar -roll Q8 is'mount'ed transversly'of frames lil' andfi' l. adj acentthe drum 94.The "outerpefipheral surface of the rolls 9i" and *Ware' tangent Withthe"planeoftheupper surface "of the table; 53m "slightly "above the said"table yo-surface. -'A"transparent"endlessbelt lllil passesioverthedrums 94 and .BE'and rollers "S'l and98 and"passes "over thesurface-of the table 33 in contact therewith.

When" the motor-8 9 is energized "to rotate in "one direction, the-worm88 'willdrive the worm gear 86, which will turn shaft 34 and pulleyt'l.The pulley. 8'!, hymeanso'f belt 90, "drives pulley -fSI"'an'clr.shaft9'2. .The'sha'fts 84 :and 92 :respecittivlymotatethe drums94 'and'95, causing the iendlesstransparent.belt"lllll'to move in onedirecitionrelative' to the'surface of tab'1ei83. Reversal ;.of"'motor 39' will. drivethe belt i 08. in the opposite direction. The outline. ofitable 183 isshown in noneunnes .l in Fig. '10 "forosimplicity," but [itwill "the evident Lthat "the ltransparent .belt' I00 may 9 move in aplane having any desired angle relative to the longitudinal axis of thetable surface 83, by either rotating the table relative to the frame I2or preferably rotating the frame 12, by means of rollers II about theaxis of the vertical shaft BI relative to the table 83.

In the operation of the cross wind simulating device, the trainerrecorder I, serving as. an indicator, is placed on the belt I and thebelt set in motion at a velocity proportional to the velocity of thewind to be simulated and having the longitudinal axis of the belt I00,making the desired angle relative to the longitudinal axis of the table83. The belt I00 will then bodily displace the recorder in a directionand at a velocity equivalent to the effect of a wind acting on thesimulated air borne trainer. The student must then correct the headingofthe trainer by an amount equal to the drift angle and as indicated inFig. 10, if line B-C represents in length to a certain scale, thevelocity and direction of the wind and A--C represents the true courseto be traversed relative to a suitable chart placed on the recordsurface 83, having a heading of angle .r, then line AB, which representsthe simulated air speed of the trainer, is the course which must besteered, to compensate for the effect of the wind component B-C and thetrainer heading and similarly the heading of the recorder must bechanged to angle y, which equals the sum of angle :r and angle z, thedrift angle. No matter what the angle between the axis of the belt I00and the longitudinal axis of the table, the effect of wind will becorrectly applied to the recorder in the same manner as the wind wouldaffect the flight of an aeroplane, simulated by the trainer 5. Whenemploying the wind simulating device above described the position of thecourse indicator marker wheel relative to a suitable chart placed on thetable 83 beneath the belt I00, serves to visually indicate to theinstructor the position of the flight trainer in its assumed flight andthe instructor gives the student the corresponding positional signal.The course indicator thus leaves no actual record on the chart of table83.

To utilize the device of Figs. 9 and 10, in the solution of interceptionproblems as in Fig. 1, two or more of the frame and table assemblies'I283, are superimposed in the manner illustrated in Figure 11, parts incommon with Figure 1 having the same reference numerals. If a waterborne target is to be operated on the upper assembly table, its tablemay be rotated relative to the belt I00, so that the effect on a targetI0, will simulate the effect of a water current, while the belt I00 onthe lower table may be arranged to simulate the effect of a wind actingon the trainer during the interception problem. With such an arrangementthe course of the target will be referred to the position indicia on thelower table surface only, the chart to be used being placed thereon. Ina similar manner the effect of Wind. on both the trainer and the airborne target 60 may be simulated. The operation of the assembly ofFigure 11 is otherwise identical to the operation of the device ofFigure 1 described above.

It is to be understood that transparent tables 83 are not essentialwhere continuous observation of the target and trainer recorder coursesis not required and in such a case the tables may be of any desiredmaterial suitable for the intended purpose. The wind simulator as notedis generally applicable to ground trainer instruc- 10 tion and is notlimited in use to interception problems.

As seen in Figs. 12 and 13, a variation of the apparatus shown in Fig. lis used to simulate air traffic control problems and the numeral fillrepresents a record table similar to the table I, illustrated in Fig. 1.The table I0i has a plurality of surfaces I02, I03, I04 and I05, insuperimposed spaced relation and preferably made of transparent materialsimilar to the surfaces 2 and 3, of the device of Fig. 1. The tablesurfaces each serve as a support for an aviation ground trainer courserecorder R1, R2, R3 and R4 respectively. Each course recorder isconnected by an electric conductor S1, S2, S3 or S4 respectively, to acorresponding flight trainer T1, T2, T3 or T4 respectively, to bedirectionally controlled thereby. The trainers are grouped around thetable and each is assumed to be flying at a different altitude from theother trainers. The course recorders are placed in operation tracing thecourse of the simulated trainer flights, which are to end at apredetermined point common to all the trainers. The instructor hastelephonic communication with each trainer and as the course recordersapproach the predetermined destination, the instructor may then giveindividual instructions as to the conduct of the flight of each trainer,so that a simulated landing can be made by each trainer in a prescribedmanner, dependent on the assumed altitude of the particular trainer. Theinstructor can watch all of the recorders and their positions relativeto the assumed landing destination and thus has complete control overthe directional information to be given in the solution of the problem.

While preferred embodiments of the invention have been illustrated inthe drawings, it is ap-. parent that other modifications can be madefalling within the scope of the invention as defined by the appendedclaims.

We claim:

1. In an aviation ground training system, an aviation ground trainer forsimulating aircraft flight, a pair of superimposed reference surfacesarranged in parallel spaced relation and at least one of said surfacesbeing formed of a transparent material, a course indicator associatedwith one of said surfaces and adapted to have a translatory movementrelative thereto at a velocity proportional to an assumed velocity ofsaid trainer and directionally controlled by said trainer, a targetobject simulating a land, air or water borne craft associated with theother of said surfaces and movable relative thereto at a velocityproportional to the supposed velocity of the craft to be repre sentedand having a controlled directional head ing, the said surfaces beingarranged such that the instant course of said target object relative tothe instant course of said course indicator is at all times apparent byvisual observation through said transparent surface.

2. The structure as claimed in claim 1, in which each of said surfaceshave corresponding positional indicia thereon.

3. In an aviation ground training system, a plurality of aviation groundtrainers for simulating the flight of aircraft, a first referencesurface, a plurality of transparent reference surfaces superimposed andin parallel spaced relation with respect to each other and with respectto said first reference surface, a plurality of course indi cators, eachassociated with one of said reference surfaces and adapted to have amotion relative to said one surface with a velocity proportional tomuseum 11 .anassumed velocity of onefof said trainers :and directionallycontrolled thereby and rence inclicia -on at least said :filiSiZlreference' sur lace, whereby the instant course of each of said courseindicators relativexto Ia pointon saidfirst reference surface is'cat alltimes apparent. by'visuai observation throughsa i'ci transparentsurfaces;

4. A wind simulating clevice for :use wi-t hxaviati'on ground trainerscomprising, .a course indicator movable relative Ito a stationary chartona supporting table surface at a velocity proportional to "ana'ssumecisvelocity in flight of :an aviation ground trainer and havingan instant ihea'ding equivalent to the heading-of said trainelgca mowable surface contacting said chart and having. "its plane of motion atany desirefil angle relative to the a longitudinal .axis of t l-1e table'surfa'ce,: movable surface having a velocity proportional to thevelocity of an assumed wind "amid a dircce tion equivalent thereto, saidcourse indicator being movable on said movable surface anddsplacedtherewith in a manner to simulate i6 efiect of an assumed wind :actingon said trainer.

5. in an aviation ground traineraassembly ,for simulating "flightinterception problems, an 'avia ti'on flight: trainer ifior simulating:.fiigntxo'f' :an aircraft, a coursefiindiicator :adap'te'd to' hav'translatory motion proportional to'an assumed velocity in flig'ht ofsaid trainer: 21d directionally controlled thereby, a :first. m'ovasurfa'ce ha-v mg. a motion equivalent to thexdirect'ionand zproportionalto ithe velocity of anassumed W-inciysaici surface supporting saiclcourse indicator for movement thereon, a target "object havingacontrollable. velocity and heading a eprcsentin g. a tare get craft, asecond movablesmztaoe tfor supportingwsa'id target object said secondmovable surface having a velocity "DT'OIJOI'IUlOl'lZlJFfiO"like velocityof an assumed cunvent' ofiche suppm' 11g medium acting onsaid'ftargetiob' ject mg;

a direction equivalent theretoysaid surfaces eing superimposed and inparallel spaced relation; the

12 upper oneiof' said'sur-faces being composed=of a transparent materialwhereby the instant positioniofssaid course indicator relative to saidtarget object 3iSi2tt' al 1 "times apparent by "visual observationthroughsaid transparent surface.

6. The structure as claimed in claim 4, in whi'chzsaid movable surfaceis a belt driven at a constant-"speed by an adjustable speed powermeans.

CARL J. CRANE. GEORGE V. HOLLOM'AN. CARL W; MULLER. RAYMOND K. STOUT.

:REFERENGES CITED.

The following references are of record in the filo of this patent:

STATES PATENTS Number Name Date 830,718 Holt Sept. 11, 1996 1293;74'7Ford Feb. 11, 1919 1,5'9'6;93'6 lvlengc'len Aug. 24, 192 130E582 MengdenFeb. 12, 1929 L -745,933 Kauch Feb. 4, 1930 1,825,462 Link Sept. 23',1931' 1,985,265 Smith Dec. 1934 1,985,266 Smith Dec. 1934 2,099,857 LinkNov. 23, 1937 -2,1I9,'083 Link May 31,193 2,131,952. House Oct. l, 19382163, 746 Courtois-Sufiit June 27, 1939' 2,164,412 Kos'ter -i July 4,1939 231711561" Hoov'en Sept. 5, M33 2,1'291663 1 Link c- Nov. 14, 19392191-1730 Sjostra nd Feb. 27. 1940- FOREIGN PATENTS Number Country Date484,243 Great Britain 19233 384,971" Great Britain 19.31

